The present invention relates to an illumination device for producing a light strip along a predetermined distance on a component.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
In order to allow a person to orient themselves also in the dark inside the motor vehicle, individual components for example a cup holder or a loudspeaker can be illuminated from their interior with a light source. The person can then recognize where the functional element is located in the interior without the entire interior having to be illuminated. The above mentioned illumination device allows distributing the light of a light source along a contour of the respective functional element so that the contour is recognizable in the dark as bright strip. Typically such an illumination device is used for a circumferential illumination, i.e. in this case the strip has the shape of a closed band.
In order to generate a circumferential light strip, a ring-shaped light conductor made of Polymethylmethacrylate (PMMA, Plexiglas®) can be used, into which light is coupled on both ends. The light conductor has the shape of the contour to be represented and can be fixed on or around the component, for example by means of a latching engagement. The light emitting diodes can each be mounted in a coupling-in element in which an electric switch is located for operating the light emitting diode and by which the light of the light emitting diodes is focuses and directed onto a coupling-in surface of the light conductor.
Along its longitudinal extension in the direction of extension of the contour the light conductor has scattering centers, i.e. for example indents on its outer walling or reflecting particles in its interior, by which a portion of the light is deflected and exits the light conductor, thereby distributing the light of the light emitting diodes along the distance. As a result, the light conductor appears evenly bright along the contour. By means of such light conductors a surface of up to 200 mm×150 mm can typically be surrounded by an evenly bright light strip.
When a larger area is to be surrounded with a circumferential light strip the light strip has to have a corresponding length. This results in the problem that thermally caused changes in length of the light conductor can cause mechanical tensions in the material of the light conductor which can lead to hairline cracks in the material or even destruction of the light conductor. In particular, temperatures of between −40 to 80° C. can occur in a motor vehicle.
It would therefore be desirable and advantageous to provide an illumination device which allows generating an evenly bright light strip along the contour of a large-surface area functional element.